As researchers seek to understand individual differences in peoples psychological resilience to life stressors, both personality traits and spirituality/religiousness (S/R) have emerged as important predictors of sustained well-being in the face of adversity, though it is not clear how these variables are jointly related to emotional well-being. Further, most research on the relation between personality traits and religiousness has been conducted in healthy, well-adjusted samples and little is known about their association in vulnerable populations. To address these gaps in the research record, in a recent study LPC/PSCS investigators examined the relative association of personality traits and S/R with mental health in a sample of people living with HIV. Research on the psychology of religion relies on a wide variety of measures to capture peoples experience of the sacred, yet a basic distinction can be drawn between religiousness and spirituality. Religiousness captures adherence to traditional religious creeds, often centered on a specific community of faith and encompasses a set of behaviors (e.g., prayer, church attendance) associated with a specific belief system. Spirituality typically refers to subjective experiences of the transcendent which imbue everyday life with a sense of deeper and may also encompass a sense of communion with humanity and compassion for others. This differentiation is particularly relevant when studying populations affected by HIV/AIDS who often face stigmatization and may be more likely to report being spiritual but not religious. We focus on the Five-Factor Model of personality traits, a comprehensive and widely replicated trait taxonomy that describes personality along the following five dimensions: Neuroticism (N), Extraversion (E), Openness to Experience (O), Agreeableness (A), and Conscientiousness (C). In previous studies, high A appears to show somewhat stronger associations to religiousness than to spirituality, high O shows the opposite pattern, high C is related to both concepts, whereas low N and high E show weaker associations to either construct. Method Participants (n=112) were paid volunteers drawn from a larger longitudinal sample and were recruited into the parent sample if they were HIV positive and had CD4 counts ranging from 150 to 500. Participants disease status was assessed via CD4 lymphocite count and viral load at baseline. Personality traits were assessed with the Revised NEO Personality Inventory (NEO-PI-R, Costa &McCrae, 1992). Spirituality and religiousness were assessed with the short form of the Ironson-Wood Spirituality/Religiousness Index (IWSRI;Ironson et al., 2002). Mental health was captured using a test battery including the Beck Depression Inventory (BDI, Beck, Steer, &Brown, 1996), the Perceived Stress Scale (Cohen, Kamarck, &Mermelstein, 1983), and others. Results Our findings suggest that the general pattern of associations between personality traits and S/R holds true across diverse samples. C showed the most consistent pattern of associations to S/R with significant partial correlations to all of the IWSRI subscales, followed by A and O. For N, significant associations were limited to the Religious Behavior scale and E was the only factor that showed no associations to the IWSRI. Evidence from facet-level analyses illustrate that religiousness is associated with low scores on Impulsiveness (N) and high scores on Altruism and Compliance (A). Also, consistently across studies, aspects of spirituality were associated with high scores on Fantasy, Aesthetics, and Feelings (O). Further, high scores on Tender-Mindedness (A) and Competence (C) were associated with both spirituality and religiousness. Personality factors and IWSRI scores were significantly associated with mental health and the general pattern suggested that N was associated with lower levels of mental health (i.e., higher levels of depression, hopelessness, anxiety and stress as well as lower levels of optimism). The remaining personality factors as well as the IWSRI subscales were positively associated with mental health. Discussion Religious and spiritual individuals feel in charge of their lives and show high levels of sympathy and concern for others. In addition, primarily religious individuals are uniquely characterized by the ability to resist temptations coupled with the tendency to de-escalate social conflicts and assist others in need. Primarily spiritual individuals, in turn, show vivid imagination, appreciation for beauty, and receptiveness to their inner feelings. Our findings suggest that when the NEO-PI-R domains are considered in combination, underlying personality traits fully account for the association of S/R with mental health, consistent with the theoretical claim that religiousness and spirituality are characteristic adaptations that develop as basic personality traits are channeled by cultural and environmental influences (source). Furthermore, a set of mediation analyses provide good initial evidence that certain aspects of S/R mediate the relationship of both O and A with mental health. Our findings also have important practical implications because the mediation analyses suggest that the benefits of S/R for mental health are largely dependent on a persons underlying personality traits. This suggests that any interventions aimed at inducing a turn towards religion in order to improve mental health may be misguided. Instead, medical professionals may want to assess their clients personality profile to determine who may benefit most from access to spiritual and/or religious support and guidance.